Fog inhibitor for photographic developers



?atented Jan. 27,, 1942 roe mmarroa non Pno'roermrnrc "DEVELOPERSWillard D. Peterson and Ralph M. Evans, Rochester, N. Y., assignors toEastman Kodak Company, Rochester, N. Y., a corporation of New Jersey NoDrawing. Application November'10, 1939, Serial No. 303,878

2 Claims.

This invention relates to photographic developers and particularly tofog inhibiting or toning agents for developers.

It is well known that fogging occurs in a photographic film or platewhen itis developed at temperatures higher than 70 F. or when developedfor unusually long periods of time. It is necessary in most cases to usea relatively weak developer in order to avoid the formation of fog.Soluble bromides, such as potassium bromide, have been used in -thedeveloper to overcome this but they do not permit development with astrong developer for long periods of time at temperatures which may gohigher than 70 F. We have discovered that certain derivatives ofindazole, for example, 5-nitroindazole and 5- aminoindazole, may beincorporated in the developer to obtain all of these advantages. Thesecompounds may be used either in black and white or in color developers.In some cases they maybe added to the emulsion or to the subbin orbacking layers of the film or plate.

Indazole has the following structural formula:-

able are 5-nitroindazole, l-methyl-fi-nitro-indazole, S-amino-indazole,5-p-.toluene sulfonamido- 5.6 parts by weight of fi-nitro-indazole aresuspended in asolutionof 1.5 parts of sodium hydroxide in 40 parts ofwater. With good stirring, 5.1 parts of dimethyl sulfate are addedslowly. The temperature is maintained at 25- 35 C. and the time requiredfor adding the di-v .methyl sulfate is approximately two hours. The

reaction mixture is always kept slightly alkaline by small additions of5% alkali, when necessary.

The compounds 5-p toluene-sulfonamido-innitrobenzoylamino-indazole areobtained by reduction of 5-nitroindazole and subsequent treatment withthe suitable acid chloride. The compound 5 benzoylacetamino-indazole isbest prepared by heating 5-amino-indazole with ethyl benzoyl acetate to165 C.-1'75 C. and distilling off the alcohol generated during thecourse of the reaction. The compound E-amino-indazole is prepared bysimple reduction of 5-nitro-indazole.

The following examples, which are-illustrative only, indicate developingformulae using nitro derivatives of indazole according to our invention.

Example 1 Ablaok and white developer is made as follows:

Monomethyl-paminophenol sulfate grams 1 indazole. 5-benzoylacetaminoindazole, and 5-pnitrobenzoylamine indazole. The structural for 'mulasof 5-nitroindazole and 1-methyl-5-nitroindazole, respectively, are asfollows:

5-nitroindazole may be prepared as follows: Y 2 parts by weight of5-nitro-2-amino-toluene dissolved in100 parts of acetic acid are treatedat C. with a concentrated aqueous solution containing 0.91 part ofsodium nitrite. The re sulting solution is allowed to stand for a dayand is then concentrated nearly to dryness. The

' residue is washed well with water to remove the remaining acetic acid.The product is obtained in pure form by recrystallization Irom dilutemethyl alcohol, and melts at 2 06-208 C.

1-methy1-5-nitroindazole is prepared as follows:

Hydroquinone' do 5 Sodiums fi do Sodium carb 30 v Potassium bromide; do.5-

5-nitroindazo do .1 Water to liter 1 In this formula the potassiumbromide may be entirely omitted since its function is performed by the 5-nitroindazole. I

Example 2 A developing solution for forming a colored image by couplerdevelopment is made as follows:

A. 2-amino-5-diethylaminotoluenehydro- In use, B is added to A. Thisdeveloper produces a blue-green dye on development of an exposed silverhalide layer. The amountjoi' the indazole derivative used in developerseither in black and white or in color developers may vary from about.005 gram to .50 gram per liter or agenhg coupler compound, and5-nitroindazole.-

higher.

ofthe appended claims.

7 2. A color-forming photographic developer We consider as within ourinvention all equivacomprising a primary aromatic amino developinglents'and modifications coming within the scope agent, a. coupler v Initroindazole.

. We claim: v v p D. PEI'ERSON.

1. A color-forming photographic developer RALPH M. EVANS.

I comprising a primary aromatic amino geveioping compound, and1-methyl-5-

